Highly Ethylene‐Selective Electrocatalytic CO₂ Reduction Enabled by Isolated Cu−S Motifs in Metal–Organic Framework Based Precatalysts

Abstract

Copper-based materials are efficient electrocatalysts for the conversion of CO 2 to C 2+ products,a nd most these materials are reconstructed in situ to regenerate active species. It is achallenge to precisely design precatalysts to obtain active sites for the CO 2 reduction reaction (CO 2 RR). Herein, we develop astrategy based on local sulfur doping of aCu-based metal-organic framework precatalyst, in whichthe stable CuÀ Smotif is dispersed in the framework of HKUST-1 (S-HKUST-1). The precatalyst exhibits ahigh ethylene selectivity in an Htype cell with am aximum faradaic efficiency (FE) of 60.0 %, and delivers acurrent density of 400 mA cm À2 with an ethylene FE up to 57.2 %i naflowc ell. Operando X-raya bsorption results demonstrate that Cu d+ species stabilized by the CuÀS motif exist in S-HKUST-1 during CO 2 RR. Density functional theory calculations indicate the partially oxidized Cu d+ at the Cu/Cu x S y interface is favorable for coupling of the *CO intermediate due to the modest distance between coupling sites and optimizedadsorption energy.

Atomically Dispersed Cu Catalysts on Sulfide-Derived Defective Ag Nanowires for Electrochemical CO2 Reduction

“…The XANES spectrum (Figure 1f) of Cu/Ag(S) overlapped with that of the Cu(II) reference, while the spectrum of Cu/Ag 2 S/Ag predominantly resembled that of a Cu 2 S reference spectrum as reported previously. 20 Specifically, the Cu XANES for Cu/Ag(S) showed an E 0 shift toward higher energy compared with that for Cu/Ag 2 S/Ag, while an increase in the white-line intensity of XANES for Cu/Ag(S) was also observed compared with that for Cu/Ag 2 S/Ag. These suggest that the Cu oxidation state of Cu/Ag(S) was higher than that of Cu/Ag 2 S/Ag.…”

Ultrasmall Cu Nanocrystals Dispersed in Nitrogen-Doped Carbon as Highly Efficient Catalysts for CO2 Electroreduction

“…These results demonstrate that the Cu/NC-NS catalyst, in which the Cu nanoparticle sizes are mainly concentrated in the 3–5 nm range, exhibits high selectivity toward ethanol and formate at different potentials. According to reports, the flow cell has the unique advantages of increasing the CO 2 conversion rate and easily generating a high current density. ,,,, Thus, for a better comparison, we further evaluated the CO 2 RR performance of the Cu/NC-NS catalyst under various high current densities from 100 to 220 mA cm –2 with 1 M KOH as the electrolyte. It can be clearly seen (Figure S9a) that the main liquid product is formate with a small amount of acetate and ethanol.…”

Operando NMR Spectroscopy Reveals an Oxygen Blocking Mechanism in Formate Electrosynthesis

“…In addition, no obvious detectable liquid products were produced except for formate and dissolved H 2 gas (Figures S4 and S5), which might be attributed to the ultralow content of liquid products in the H-type cell. 24 Next, the percentage of the formate product produced by the Nano Cu system was evaluated using the proposed operando electrocatalytic NMR spectroscopy technology based on 1 H NMR signals. As shown in Fig.…”